In general, an image forming apparatus using an inkjet recording method needs to remove foreign material such as remaining ink, dust, and paper powder from a nozzle face of a discharge head (e.g., recording head) to secure a good image quality for image printing.
Conventionally, foreign material such as ink, dust, and paper powder adhered on the nozzle face of the discharge head (e.g., recording head) can be removed by a removing member such as a wiping blade made of rubber, for example.
Such rubber-made wiping blade can be made of materials such as silicone rubber, urethane rubber, hydrogenated nitrile butadiene rubber, ethylene propylene diene monomer (EPDM), and fluorine-containing rubber, for example. In addition, the wiping blade can be made of rubber having vulcanizing agent.
As for water repellency, which covers the nozzle face of the recording head (e.g., inkjet head), materials such as silicone resin, acrylic resin, fluorine resin, silicone modified fluorine resin, silicone modified acrylic resin, fluorine modified silicone resin, fluorine modified acrylic resin, acrylic modified silicone resin, acrylic modified fluorine resin can be used, for example.
The wiping blade contacts the nozzle face of the discharge head (e.g., recording head), thereby a friction occurs between the wiping blade and the discharge head.
Accordingly, the nozzle face needs friction-resistance or abrasion-resistance to prevent damages on the nozzle face, and the wiping blade also needs abrasion-resistance (e.g., anti-wear, anti-tear).
With such requirements, a fluorine resin having good lubricousness is conventionally used as the water repellent to cover the nozzle face.
FIG. 1 shows a schematic view when the wiping blade removes (or scrapes) foreign materials (e.g., ink) adhered on the nozzle face of the discharge head (e.g., recording head).
As shown in FIG. 1, a wiping blade 11 cleans a nozzle face 12 when the wiping blade 11 removes (or scrapes) ink 13 from the nozzle face 12. The wiping blade 11 moves in an arrow direction shown by “X” in FIG. 1.
If physical contact of the nozzle face 12 and the wiping blade 11 is tight, ink may not sneak through the wiping blade 11, thereby remaining ink 14 may not appear on a backside of the wiping blade 11 with respect to a moving direction of the wiping blade 11.
However, a complete physical contact of the nozzle face 12 and the wiping blade 11 is hard to attain due to reasons such as bumping of the wiping blade 11 on foreign materials (e.g., paper powder, fixed ink), bumping of the wiping blade 11 on a nozzle cover (not shown), smoothness level of the nozzle face 12, and irregularities on the wiping blade 11.
FIG. 2 shows a schematic view when the wiping blade 11 cleans the nozzle face 12 of the discharge head (e.g., recording head), but some ink is still adhered as remained ink 14 on the nozzle face 12.
If a gap between the wiping blade 11 and the nozzle face 12 is relatively small and the nozzle face 12 has relatively high ink repellency, ink may not sneak through the gap so easily.
However, if the gap is too large, ink may sneak through the gap easily, and resulting in remaining ink 14.
Such gap may be generated between the wiping blade 11 and the nozzle face 12 by reasons such as abrasion (or wear and tear) and scratches, which may happen on the wiping blade 11 and the nozzle face 12.
With repeated cleaning operations of the wiping blade 11 on the nozzle face 12, abrasion (or wear and tear) or scratches may happen on the nozzle face 12, thereby a gap may be unfavorably generated between the wiping blade 11 and the nozzle face 12.
Such gap may be generated significantly if the wiping blade 11 does not move on the nozzle face 12 smoothly (i.e., higher friction coefficient between the nozzle face 12 and wiping blade 11).
Generally, a fluorine resin having good lubricousness is preferably used as the water repellent to cover the nozzle face 12.
However, fluorine resin may not be preferable as a material for covering a surface of nozzle (e.g., nozzle face 12) because of a relatively high material cost.
Furthermore, the manufacturing yield of nozzle pieces is relatively lower because a nozzle has a complex shape but is required to be manufactured with higher precision dimensionally, thereby fluorine resin may not be preferable as a material for covering a surface of nozzle.
If the water repellent material covering the nozzle face of the discharge head (e.g., recording head) provided in an image forming apparatus of inkjet recording type has a good lubricousness such as fluorine resin, the nozzle face can secure anti-scratchness and abrasion-resistancy (e.g., anti-wear, anti-tear) even if a friction coefficient of the wiping blade is not so small.
Furthermore, the wiping blade can also secure abrasion-resistancy (e.g., anti-wear, anti-tear) if such water repellent material having a good lubricousness is used.
In view of such background, a discharge head (e.g., recording head) having a nozzle face, covered by less expensive water repellent material, has been desired because of the relatively expensive cost of fluorine resin.
Such less expensive water repellent materials having enough ink repellency includes silicone resin, for example.
Furthermore, in order to improve discharge stability of recording fluid (e.g., ink) having a smaller surface tension and rapid permeability, it is desired to employ a material having a higher ink repellancy than conventional fluorine resin to cover a nozzle face of a discharge head (e.g., recording head).
Materials having higher ink repellency include silicone resin, silicone modified acrylic resin, silicone modified fluorine resin, and fluorine modified silicone resin, for example.
These polymers having silicone polymer chains have relatively higher ink repellancy but lower lubricousness compared to fluorine resin, and also have a relatively lower hardness, thereby such polymers may unfavorable to preserve abrasion-resistancy and friction-resistancy of the nozzle face.
Furthermore, the wiping blade may show unfavorable phenomenon such as abrasion (or wear and tear) if such polymers are used.